Integrally bonding a decorative sheet to the surface of an injection molded resin article simultaneously with the injection molding thereof has conventionally been performed (see Patent Document 1, for example). FIG. 8 shows a foil-decorating injection molding apparatus disclosed in Patent Document 1, and FIG. 9 shows a perspective view of a portion of the apparatus in the vicinity of a female mold. The foil-decorating injection molding apparatus 100 comprises the female mold 2 with a contour corresponding to a desired article to be obtained, and a male mold 20. The bottom of the female mold 2 is fixed to a movable platen 5 such that the female mold 2 can be moved towards or away from the male mold 20 by a fluid pressure cylinder ram 7.
The female mold 2 is formed with a cavity 4 with a contour corresponding to the shape of the desired article to be obtained. In the cavity 4, there are bored vacuum suction holes 17 that open out to the cavity 4 and which lead to an external vacuum pump via a vacuum suction passageway 14 bored in a bottom portion of the female mold 2 and via a conduit 15. The female mold 2 is also fitted with a rectangular frame clamper 110 for pressing and fastening a decorative sheet S onto a parting surface 2a of the female mold 2.
On the other hand, the male mold 20 is fixed to a fixed panel 25 in which a nozzle 28 of an injection molding machine is mounted. The male mold 20 is provided with a protruding portion (core) 21 at the center corresponding to the shape of the article. In the protruding portion 21, there is formed a runner 22 for injecting a molten resin into the cavity 4 of the female mold 2 via the nozzle 28 of the injection molding machine.
Above the female mold 2, there are provided a reel 70, a guide roller 74, and a pair of feed rollers 72 for winding and rewinding an elongated band of a decorative sheet RS that is wound in a roll. A transport chuck 130 is disposed between the feed roller 72 and the female mold 2 for feeding a decorative sheet S onto the parting line 2a of the female mold 2. On the lower side of the female mold 2, there is disposed a receiving chuck 50 for receiving an end Sa of the decorative sheet S that has been transported via the transport chuck 130.
When performing an injection molding and foil decoration simultaneously using this apparatus 100, the elongated band of the decorative sheet RS wound in a roll is drawn out by the feed rollers 72. A decorative sheet S is then clamped by the transport chuck 130 near the end Sa of the sheet, as shown in FIG. 9. The transport chuck 130 is then transported vertically downward in a plane parallel to the parting surface 2a of the female mold 2, until the very tip of the end Sa of the decorative sheet S protrudes downward just a little beyond the lower end of the receiving chuck 50.
Then, the end Sa of the decorative sheet S is grasped by the receiving chuck 50, and, as shown in FIG. 10, the transport chuck 130 is released, raised, and brought back to the initial standby position shown in FIG. 9. The decorative sheet S is then pressed and fastened onto the parting surface 2a of the female mold 2 by the clamper 110. Thereafter, a heating panel 80 that has been withdrawn from the areas between the female and male molds is now brought closer to the clamper 110 until it is directly opposite thereto so that it can heat and soften the decorative sheet S, as shown in FIG. 11.
A heated-wire type sheet cutter 90 is provided on the upper end of the heating panel 80 via an L-shaped support member 92 such that the cutter 90 protrudes beyond the heating panel 80 and the clamper 110 towards the female mold 2. As the heating panel 80 is moved and brought into contact with the clamper 110, the decorative sheet S is cut in the direction of the width thereof by the sheet cutter 90, and a single-shot length of the decorative sheet S at its end can be cut off from the upstream portion of the sheet. The tip portion of the decorative sheet S from which the single-shot length has been cut off is later wound back to the position (see FIG. 12) where it is grasped by the transport chuck 130 in preparation for the next shot.
Simultaneous with, or immediately after the decorative sheet S heating/softening step, the decorative sheet S is vacuum-sucked via the vacuum suction holes 17 formed in the female mold 2 so that the decorative sheet S is stretched in conformity with the cavity 4 of the female mold 2 in an airtight manner. Following this stretching step, the female mold 2 is moved towards the male mold 20 for mold clamping in a mold clamping step. This is followed by an injection molding step (see FIG. 12) in which an injection molding resin in a molten or in an uncured, liquid state is injected into the cavity 4 formed between the female mold 2 and the male mold 20 via the runner 22 in the male mold 20. A mold opening step is then conducted in which the female mold 2 and the male mold 20 are separated, followed by a removal step in which a molded article P to which the decorative sheet S is integrally bonded is removed from the female mold 2.
The decorative sheet may employ either a laminate sheet or a transfer sheet, depending on the type of the desired product. In the case of using a laminate sheet, the laminate sheet per se will have been foil-decorated by injection molding, resulting in the entire layers of the sheet being integrally bonded to the surface of the injection molded resin article and creating a pattern layer. On the other hand, when the decorative sheet is a transfer sheet, a support sheet is peeled from the pattern sheet that has been integrally bonded to the surface of the injection molded resin article, whereby only a transfer layer of the pattern layer, for example, is left behind on the injection molded resin article, thereby creating a pattern layer and completing the foil-decorating process.
Instead of the receiving chuck 50 in the above-described apparatus 100, a second clamper may be provided adjacent to the first clamper (see Patent Document 2, for example). FIG. 13 shows a major portion of the foil-decorating injection molding apparatus disclosed in Patent Document 2, where a second clamper 250 is provided beneath and adjacent the first clamper 210. In this apparatus, the decorative sheet S that has been fed onto a female mold 202 by a transport chuck 230 is grasped by the second clamper 250 and, after the transport chuck 230 has been returned to the initial standby position as shown, the decorative sheet S is pressed and fastened onto the female mold 202 by the first clamper 210.
(Patent Document 1) Japanese Patent No. 3093159
(Patent Document 2) Japanese Patent No. 2714258